Oakland Athletics right-hander Bartolo Colon has been suspended 50 games after testing positive for testosterone, the commissioner's office announced Wednesday.

The suspension, due to violating the league's Joint Drug Prevention and Treatment Program, is effective immediately.

Colon, 39, is 10-9 with a 3.41 ERA this season for the Athletics. He won the 2005 AL Cy Young Award while with the Angels.

"The Oakland Athletics are disappointed to learn of today's suspension of pitcher Bartolo Colon," the team said in a statement. "The organization fully supports Major League Baseball's Joint Drug Prevention and Treatment Program and its efforts to eliminate performance-enhancing substances from our game. Per the Basic Agreement, the A's will have no further comment."

Colon's suspension comes one week after All-Star Game MVP Melky Cabrera was suspended for 50 games without pay after the San Francisco Giants outfielder tested positive for testosterone.